HealthDay News — The quadrivalent human papillomavirus (HPV4, Gardasil, Merck) vaccine appears safe and effective for adolescents, according to research published in Pediatrics.

To examine the long-term safety, effectiveness, and immunogenicity of the HPV4 vaccine, Daron Ferris, MD, of Georgia Regents University in Augusta, conducted a cohort study involving 1,781 sexually-naive patients aged 9 to 15 years.

Participants were randomly assigned HPV4 vaccine or saline placebo at day one and months two and six. At month 30, the 482 participants in the placebo group received HPV4 vaccine and followed the same regimen.

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Vaccination-induced anti-HPV response persisted through 96 months for each of the HPV4 vaccine types, according to the investigators. None of the 429 subjects who received HPV4 vaccine at a mean age 12 years developed HPV6/11/16/18-related disease or persistent infection. Among patients aged 16 years or older, acquisition of new sexual partners was about one per year.

The baseline rate of seropositivity to one or more of the four HPV types was similar for those receiving the vaccine at month 30 (1.9%) and for those vaccinated at day one (1.7%). Four of nine patients vaccinated at the later age were seropositive to three vaccine types.

“When administered to adolescents, the HPV4 vaccine demonstrated durability in clinically effective protection and sustained antibody titers over eight years,” concluded the researchers.


  1. Ferris D et al. Pediatrics. 2014; doi: 10.1542/peds.2013-4144

Disclosures: Several authors disclosed financial ties pharmaceutical companies, including Merck, which funded the study.